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TORONTO – A dizzying video of two Russian men climbing the second tallest structure in the world is so vertigo-inducing it’s almost impossible to watch.

On Wednesday, Vadim Makhorov and Vitaliy Raskalov posted a video of themselves climbing China’s tallest building. The climbers scaled the unfinished building, which stands just over 650 metres tall, without the assistance of ropes or climbing gear.

According to a blog post, the climbing daredevils scaled the building on Jan. 31, Lunar New Year’s day, a public holiday in China.

It took the pair nearly two hours to reach the 120th floor, where they spent almost 18 hours waiting for better weather before climbing the crane, according to the blog post.

“I’ve been on a lot of roofs,” Rasklalov told ABC News. “But this was the most beautiful. When I saw just the two other buildings sticking up from the clouds, it was like flying in a plane. It was f—— awesome!”